US2583072A - Derrick - Google Patents

Description

Jan. 22, 1952 Filed Sept. 9, 1944 J. H. WILSON DERRICK John Hart Wilson Guam;

Jan. 22, 1952 J wlLsoN 2,583,072

DERRICK Filed Sept. 9, 1944 8 Shets-Sheet 2 Jan. 22, 1952 H w so 2,583,072

DERRICK Filed Sept. 9, 1944 8 Sheets-Sheet 3 Jan. 22, 1952 I J; wl so 2,583,072

DERRICK Filed Sept. 9, 1944 8 Sheets-Sheet 4 110/112 Hm'i Wilson Jan. 19

Filed Sept 9' 1944 DER 8 Sheets- 5 "IA IIIIIII ozz Jan. 22, 1952 J. H. WILSON 2,583,072

DERRICK Filed Sept. 9, 1944 8 Sheets-Sheet 6 Jan. 22, 1952 J. H. WILSON 2,583,072 v DERRICK Filed Sept. 9, 1944 8 Sheets-Sheet '7 U WW, 16 V JOIZIZ HCZIfWZZSOIZ J 1952 J. H. WILSON 2,583,072

DERRICK Filed Sept. 9, 1944 8 Sheets-Sheet 8 woe/WWO" John Hart WiZSOIZ Patented Jan. 22, 1952 UNITED STATES EATENT OFFICE DERRICK; J ohn ar i sQ i iQ ii a Eall ljT i ,onnlica i nssntcmb %.S r aLN 553,396

16 Claims.

This invention relates to derricks, more particularly to portable derrickscomposed of prefabricated units adapted for assembly on location, and constitutes a continuation-in-part of my application Serial No. 423,211, filed Decemher 6, 1941, now abandoned.

Economical production of oil from many oil fields requires employment of derrick structures for oil well maintenance purposes. Thousands Of such derricks have heretofore been and are now being used, these structures varying widely in size, general design and in detail of construction. Some are erected of wooden members, others of structural steel, and some are fabricated in part of wooden members and in part of steel members. -Oil field derricks vary considerably in height but generally speaking, most of them lie within a range'of from 84 to 122 feet in height. For servicing deeper wells heights of 136 to 180 feet are sometimes required.

It is practically standard practice to construct such derricks as truncated pyramids each with four principal or corner members which are inclined upwardly and inwardly toward a common vertical axis. Because of the very considerable heights of these structures the practice hitherto has been to erect them as other buildings are constructed, 1, e., by superposing part upon part and section upon section, bolting each such part in position as it is placed, beginning with'the base structure and working upwardly to the crown. Erecting a derrick of any appreciable height requires a considerable expenditure of ime h n o u t n n t e nner a o scribed. The process is costly even when preiabricated parts are. used and a very considerable element of risk to the erection crew is inowe It is the purpose of the present invention to provid a mat ria ly m oved. de i k tr u f the e abri t pe w ich i o su h aracte tha i may be c ed m qu c y than similar structures heretofore pIODQS d or used, which may be erected at considerably less expense t an ea l er ty e of s ri a wh is of such char ct r a co t ucti n atthe elemen of dan r o the e ct cr w wh l ass mlin i r a y r uced- The m rovedde ri s now tq i c te ar icularly d scribe is f a omple e y act ry made p fa r ca ed y e ea h d ry of its p rts bein construc d a h p n of a f cator. its various parts are so designed that ey y be g uped t e er in sub-as emb i oc upying v,Iiii iiiWm spac when bein an ported so that a complete derrick, capable of extension to heights beyond feet, may be very conveniently transported to the location where it is to be erected. On location the subassemblies may be quickly positioned in proper relationship to each other and to the well platform, and final assembly quickly eifecteol Without the use of bolts. The derrick is fireproof, embodying metal parts only, and its various component elements are so designed that it may be disassembled as quickly as it may be assembled when its usefulness at any particular location is past, and transported 'to another location to be there erected as before and used in its new location so long as may be necessary.

In accomplishing the above described broad objectives 1 have evolved various new and usefu l structural features and relationships which cooperate to obtain the desired results in a more facile, eiricient, and inexpensive manner than has heretofore been possible. Furthermore, the invention comprises a new and improved method of assembly and erection which at once greatly reduces the time required for that operation and the hazards to which the crew is subjected during the assemblyand disassembl operations.

Among the important features of'the invention which contribute to obtaining the above described desiderata are a simplified and reliestive arrangement of telescoping legs together with readily manipulable mechanism whereby inner legs :may be extended individually from any of a number of operating points and with relatively little elfort. 'In this manner the particular sequence of steps, insofar as successively erecting the various telescoped units is concerned, may be varied as to timing, etc, wherever occasion demands without in'any way interfering with the broad sequence of operations.

Another important feature which contributes substantially to the simplicity of the erection operation and the rigidity thereof after erection is the m ro ed t oi gir d sc o d er the particular manner in which it cooperates with the derrick legs to insure rigidity after positioning. The ease wi h h ch th se side m be P a semb ed a d r sequea l as d n the proper relationship with the derrick legs greatly fac l ta e th speed i e ect on- An im or an phase Q the invention r de n the which the c own a s bl post tioned with reference to the derrick legs after the latter have been fully extended. One aspect of this phase resides in the particular manner in which the gin poles for supporting the hoist mechanism located at the top of the derrick are initially positioned prior to erection and the manner in which, after the leg sections have been fully extended, they are located and fixed with reference to one another with a minimum of eifort and manipulation on the part of the crew. Certain adjustment features are important to this aspect of the invention.

Still another phase of the manner in which the crown assembly is positioned with.reference with reference to the gin poles aforesaid. My improved arrangement for accomplishing this, and the particular cooperative relationship of the structural parts involved permit the placement of this section with the greatest ease and a minimum of risk to the crew who, under such circumstances, are working at considerable heights.

Another feature of importance resides in the locking mechanism whereby various portions of the assembly may be quickly and securely fastened together, and whereby, when once positioned, the force of gravity functions to preclude any possible dislodgment from the relative positioning of the parts except when the locking pin is positively manipulated against such force.

As hitherto suggested, one of the most important aspects of this invention resides in the particular method or sequence of steps involved in erecting the prefabricated units whereby the same are properly assembled with reference to one another without undue difficulty and with a minimum crew utilizing no more than the power that is usually available under such circumstances for operating and servicing the well when completed.

Various other objects and meritorious features of the invention will be apparent from the following description taken in conjunction with the drawings, wherein like numerals refer to like parts throughout the several figures, and wherein:

Figure 1 illustrates one of the early stages of erection, the base leg sections and the first telescopic extension of each being in position;

Fig. 2 illustrates a further stage of erection wherein three te escopic sections of each leg are in extended position;

Fig. 3 illustrates the derrick fully assembled, although somewhat diagrammatically;

Fig. 4 is a perspective illustrating particularly the manner of positioning my improved girts and the gin pole structure at the t p of the derrick;

Fig. 5 is a vertical section through one set of supporting legs in telescoped position;

Fig. 6 is a transverse section therethrough;

Fig. 7 is a vertical section through the base of the telescoped leg sections complementing Fig. 5 and illustrating the means for raising the telescoped sections successively;

Fig. 8 is a section illustrating how each leg section is held in extended position;

Fig. 9 illustrates an improved girt assembly, partially broken away and in section, positioned with reference to two adjacent leg sections;

Fig. 10 is a section through a leg section illustrating the action of a girt clamp in positioning a girt with reference to a leg section;

Fig. 11 is a side elevation of a girt clamp in locked position;

Fig. 12 is a sectional view illustrating the pin lock by which each clamp is positioned with reference to its respective supporting leg section;

Fig. 13 is a perspective of a locking pin per se; Fig. 14 illustrates, partially in section, improved means for detachably connecting one end of a girt to a leg section;

the invention resides in to the extended legs and v next adjacent inner leg section passes.

Fig. 15 is a side elevation of the top or crown supporting leg section;

Fig. 16 is a top plan view of the structure illustrated in Fig. 15;

Fig. 17 is a vertical section therethrough;

Fig. 18 is a section through iii-l8 of Fig. 15;

Fig. 19 is a top plan view of the gin pole assembly at the top of the derrick structure;

Fig. 20 is an exploded view thereof illustrating the manner of positioning the gin poles;

Fig. 21 is a perspective of the gin pole top shown at the lower left of Fig. 19;

Fig. 22 is a section through 22-22 of Fig. 19;

Fig. 23'is a top plan view of the crown block assembly;

Fig. 24 is a side elevation thereof illustrating the manner of positioning;

Fig. 25 is a plan view illustrating the initial stage of assembly and erection;

Fig. 26 is a side elevation illustrating subsequent stages of erection;

Fig. 27 is a perspective illustrating a complete base assembly and its manner of erection;

Fig. 28 is an elevation of a hoisting arrangement whereby the transformation from the position illustrated in Fig. 25 to that illustrated in Fig. 27 is obtained, and

Fig. 29 is a top plan view of one of the braced gin pole and pulley sheave assemblies used for such hoisting.

When completed and ready for operation on an oil field location the derrick appears as shown somewhat diagrammatically in Fig. 3 of the drawings and may be said to comprisea rectangular base structure upon which a pyramidal superstructure rises to a considerable height. The base is broadly indicated by the numeral 10 and the pyramidal superstructure erected thereon comprises four extended telescopic supporting legs, each of which in the form illustrated consists of sections l2, l4, l6 and [8. Upon this superstructure is positioned a crown assembly broadly designated by the letter E. The base construction, the crown assembly positioned at the top of the superstructure, and the method of erection will be taken up in greater detail hereafter.

The telescoping arrangement of the four leg sections and the manner of extending them successively to the positions illustrated in Figs. 1, 2 and 3 may be most clearly described in conjunction with Figs. 5, 6 and 7, wherein the leg sections l2, l4, l6 and iii are illustrated in collapsed position. Each telescoping section is generally tubular in cross section and, in the form illustrated, each of the sections [4, l6 and I8 are of successively reduced outside diameter with respect to base section .12 so that when the tubes are nested there is a space, crescent-shaped in cross section, between the outer surface 1 each inner tubular section and the inner surface of the next adjacent outer section forming a passage through which hoisting cables 26, 28 and 30 pass freely.

Caps 32 are slipfitted over the upper ends of sections l2, l4 and I6 and each is positioned by means of several cap screws 20 which pass through openings in the wall of the cap into drilled and tapped holes in the wall of the leg section. Each cap has welded thereto or formed integrally therewith a bracket 34 embodying bifurcated arms on which is journalled a pulley 36 over which the hoisting cab-1e connected to the Associated in similar manner with each cap 32 andbeabove, the elements are laid out on the derrick floor and the tongued end of each girt is inserted between the arms of the socket on the next adjacent girt and pinned together until the four girts form a-complete square frame. The jaws of the clamps 58 are then opened for all four of the derrick legs and, as shown in Fig. 4, hoisting lines or cables 96 are passed over pulleys secured to the upper ends of diagonally disposed leg sections. The free ends of the two hoisting lines 96 are split and the end of each split portion is secured to the middle of adjacent girts 56 in some suitable fashion. To avoid any tendency of the frame to warp out of its preformed square formation and thereby assume a'more or less diamond shape, a rod adjustable as to length, such as a turnbuckle rod 98, may be connected to diagonally opposite corners of the assembled frame. Other means of preventing distortion of the squared frame may be utilized but the one illustrated herein has been found very satisfactory.

As the girt frame is hoisted by means of the two hoist lines 96, the open jaws of the clamps at the four corners of the frame assembly function in conjunction with the leg sections as guides to position the frame with reference to the superstructure. When the frame has reached the desired position it is held there while pins 90 are inserted through the openings in the lugs on each clamp and corresponding openings in the wall of the leg section with which they have been brought into registry. The jaws 64 and 66 are then closed about the leg section and tightened in the manner aforesaid.

While ladders must be provided to permit the crew to follow the erection of the derrick, my arrangement eliminates the need for ladders on other than two diagonally opposed legs of the superstructure. In Fig. 4 I have shown ladders I and I02 secured by means of brackets I04 to upper leg sections I8. No ladders are required on the other legs because of my improved arrangement, assembled on the ground in conjunction with the girt frame assembly, permitting a crewman to cross from one leg of the derrick to another. This is accomplished by hanging a bar I06 consisting of a piece of pipe or angle iron from two oppositely disposed girts 56 by means of chains I08. The most convenient time for attachment is immediately after the girt frame assembly has been lifted a few feet from the derrick floor. Brace members IIO may be conveniently attached at the same time to the lower of ears H2 and H4 associated with each tubular girt 56 adjacent a clamp 58. The opening in upper ear II2 serves to anchor a brace member extending from a clamp 58 on the girt immediately above.

,Bars I06 are slotted at each end as indicated at H6 and one end of a chain H8 is welded to each end of the bar adjacent the extremity thereof. The other end of each chain H8 carries an eyebolt I20. This arrangement enables a crewman operating from ladder I02 or I00 to first position the immediately adjacent clamp 58,

lyillustrated in Fig. 4.

Prior to the initial stages of erection,,gin poles I are attached to the top'leg section I8 of each telescopic assembly, each pole being seated in a socket provided at the upper extremity of said top section. Referring now more particularly to Figs. 15-18, the manner in which these gin gin poles are associated with the upper ends of the top leg sections and the manner of supporting the crown assembly E will be more clearly understood. Secured as by welding to the upper end of each upper leg section I8 is a member, preferably in the form of an integral casting, which includes a socket I22 adapted to receive the lower end of a gin pole I24 and a bracket I26 in which is journaled a pulley I28 for use in raising the girts, etc. Each gin pole, preferably in tubular form, has welded to it a collar I30 which includes threaded bosses I32 and I34 110- is associated may be minutely adjusted for accuracy by manipulation of the screws. Ears I40 and I42 are secured to the member which includes socket I22, as by means of welding or otherwise, and are for the purpose of securing brace rods.

Over the-upper end of each upper leg section I8 is seated a plate I44 which may be welded in place or otherwise secured. This plate is provided with a socket I46 tapered with respect to the axis of the leg section and. adapted to receive a locating pin on one of the elements of the crown assembly and apertures I48 adapted to re-' ceive crown bolts extending from the crown block base beam, as willv be more fully brought out hereinafter. On diagonally opposite leg sections I8, as with corresponding lower leg sections, ladders I00 are secured as by means of brackets I04.

In Figs. 19-22 I have illustrated the manner in which the upper extremities of the ginpoles are brought together and positioned with reference to one another. The gin poles I24 are identical except for their upper extremities. At the extremity of one pole there is a top plate I50 to the underside of which is secured as by welding a cross plate I52. On each side of the cross plate and at an angle of thereto are secured supplemental cross plates I54 and I56, thus forming four squared sockets on the underside of plate I50. Cross plate I52 is provided with an opening I58 in which the block for raising the crown may be secured.

Each of the other three gin poles is provided with atop plate I60 with an angle iron I62 welded to the lower face thereof, each angle iron I62 being'adapted to slide into one of the squared sockets provided on the underside of plate I50. In the top plate I50 are three screws I66, each of which is adapted to bear respectively on a plate I60 of one of the three gin poles fitted into the squared sockets beneath plate I50. Each against the top plate I60 immediately beneath it to such an extent that each leg will support any equal portion of the load, thus distributing the 9v same accurately over thefour gin poles and insuring rigidity of the entire crown block assembly. The gin pole with the squared sockets'below plate I50 is raised first and asthe other leg sections I8 are extended the plates I66-I62 of the gin poles supported thereby slide'automatically into the squared sockets; The-adjustment-of screws I66 is made after all the pole sections are in positionwith reference to one-another; If necessary each gin pole i24 may be rotated slightlyin its socket I22 to facilitate alignment in the squared sockets under platelet by means ofthe screws I3'6and I38.

The crown block assembly and the manner of positioning it are most clearly illustrated in Figs. 23 and 24, from which it will be observed that the base comprises an H-shaped girder embodyingend pieces 'I Stand I10 joined by across member I12. Positioned longitudinally on cross mem- -ber I12 is a beam I14 to which is secured a suitable framework I16 within which a series of pulleys or sheaves I18 is journaled upon a spindle 180. A U bolt I82 is secured to the top center of framework I16. This may be utilized in conjunctionwith a pulley secured in opening I53 between the upper ends of the crown block assembly.

Tapered pins'I84 are seated in the underside of end members I68 and I10 at each extremity thereofand these are adapted to seat in sockets I46 in plates I44 supported at the upper extremginpoles I24 .to hoist :ity of veach upperleg section I8. Thus the crown assembly may be located very quickly and simply. If necessary, leg sections I8 may be pulled inwardlyor outwardly by means of suitable mechanical means, such as turnbuckles. However, .it hasbeen foundthatthelocating pins .184 in the bottom of the crown block girder enter the sockets J46 with little maneuvering or eiiort onsthe part of the crew.

I-tis sometimes necessary forthe crew to get up on thetop of the sections.I6 of the derrick, and rotateby chain. tongs or otherwise the top leg sections I8 since there is a tendency for the gin pole legs I24 to rotate sections I6 out of the planenecessary to bring the pole legs together properly. This may readily be overcome bystandingonbar I llfiand then turning-the respective leg sections 1 Illv toproperly center the-gin polelegs.

Openings I86 are provided at theends of each end girder I68 and H10, these openings being so positioned that when the crown block has been located andseated upon plates I44 they register .withopenings I48 therein. Bolts are positioned in thealigned openings, thereby securing the crown assembly firmly to the superstructure of the derrick. In many instances it will prove advantageous'to s construct the locating pins I84 that they are removable fromthe crown block after the same has been bolted to the superstructure.

Having described for the most part all of the articulated units of the assembly and the manner inwhich they cooperate withxone another on complete assembly, it, is now advisable to describe the new and improved method and means whereby the assembly is erected on location toobtain the finished-structure illustrated somewhat diagrammatically in Fig. '3 of the drawings.

Referring now to. Fig. 25, the base in the usual case will comprise three rectangular portions placed side by side toform a square. The outermost or'base leg sections I2 of the telescoping tubes'which form the legs are 'hingedly secured to the corners of the base structureas indicated at 10 W8, pairs of adjacent sections I 2 being hinged about axes that, coincide with one another so that they may be moved upwardly in unisonabout said axis.

It should be understood that the assembly as illustrated in Fi is formed on the ground, or,

if the derrick is supported on a superstructure,

then suitable supports such as horses will be used to support the extended portion of the derrick. Girts 52 and brace members 5% are positioned as indicated before any further steps toward erection are taken. Gin poles I90 and I92 are secured to cross members I64 and l 96,1espectively, which cross members are in turn securely fastened to the walls of the central rectangle forming a portion of the superstructure base. These gin poles connected at their upper extremities by means of a girt I98, each end of which may be secured to one of the poles bya pin lock 2% extending through the end of the pole and the ears of bracket 262, as illustrated in detail in Fig. '29.

At the top of each gin pole and on opposite sides thereof are pulley assemblies 2534- These assemblies are so secured to the top of each gin pole that the pulleys lie in substantially the same plane. On opposite sides of the base of :thevgin pole are pulleys 236 each of which is positioned on a plane normal to'the plane of the two upper-pulleys.

Ears 2ll3 of each pulley assembly 204 are provided with openings 2% and 216. The rectangle formed by gin poles I96 and I92 and girt I 88is here 2I2 and 2 I4 which extend from openings 208 in the respective poles and are secured to the base frame.

Erection cables 222 are likewise secured in openings -2I6of pulley assemblies 264 and constitute anchor points against which the tension of the erection cables operates. Erection cables 222 from their point of fixed securement to the pulley assemblies 2% pass through pulleys 224 secured to the upper portion of the respective base legsections I2, thence around the respective pulley assemblies 25M, downwardly to corresponding pulley 205, and thence to a hoisting winch not illustrated.

The poweredends of erection cables 222 connected to base pairs of adjacent'leg sections I2 lying on the same side of the girt frame II92-I98 are operated from the same side of the assembly. Thus one pair of erection cables 222 lying on one side of the rectangle formed by the gin pole and girt assembly functions, when hoisting poweris applied by the winch, to raise a section of the superstructure lying on one side of the base frame when laid out and assembled as in Fig. 25. The other pair of erection cables 222 when powered by-the hoisting winch functions to raise that section of the superstructure lying on one end to two of the leg sections I2 so that they may be easily positioned and secured after the two sides have been erected to the positionillustrated in Fig. 27.

It has been found advisable to raise one side section at a time instead of attempting to pull them both up together. To prevent the base from lifting on the opposite side from that to which the the opposite section is initially raised section is pivoted, both sections are placed in readiness for raising and tension is then placed on the erection lines 222 of one side section. While holding this tension with a brake, raised by its set of erection lines 222. When the second section is raised the weight of the section already erected is sufi'icient to hold down that side of the derrick base frame while the second section is being raised. This procedure eliminates the need for crewmen directing their attention to both side sections at the same time and likewise cuts down on the power required of the raising winch.

There is a tendency for the side frames or sections when raised to fall over toward the inside of the frame. To prevent this I propose to use jacks of some suitable type, such as the screw jacks 226. These jacks are used substantially as a brace rod, one for each base leg section I2. Just before each leg section reaches a vertical position the jack is attached to the leg as illustrated in Fig. 27, the base end of the jack bearing against a corner of one of the base cross beams. By operating the jack as occasion demands, each leg can be eased over to its ultimate position without the necessity of guy ropes located outside the superstructure.

When the last two girts 52 at the topof the base section of the superstructure are being secured these jacks can be used to push the leg sections I2 outwardly or allow them to fall inwardly, as may be necessary, so that the pins by which the girts are secured to the ears extending from the top of base sections I2 may be slid easily into the openings provided therefor.

As will be apparent from Figs. 25, 26 and 27, the gin poles I24 are inserted in the sockets provided therefor at the top of each innermost telescopic leg section I8 while the same are on the ground on location and before any step in the actual erection is carried out.

Having completed the sub-assembly as illustrated in Fig. 27 and positioned the same securely by means of girts 52, the leg sections I4, I6 and I8 are successively raised by means of cables 25, 28 and 30, girts of the improved type embodying clamps 58 being used at the top of each of the leg sections above base leg section I2. It is desirable also to utilize one of the improved type girts intermediate the ends of the top section IS where the leg sections are of suflicient height to render increased rigidifying toward the top desirable. Brace rods III) are preferably secured to the ears on the clamp members 58 prior to erection, i. e., while the structure is on the ground on location in the position illustrated in Fig. 25. The free ends of these are left dangling as illustrated in Fig. 4 as the respective leg sections are raised. After each section is fully raised and positioned the free extremities of the braces can be connected to the ears associated with the girt braces 58 of the adjacent lower girt.

When all the leg sections have been fully extended the gin poles I24 are positioned as illustrated and described in connection with Figs. 19-21, whereupon the crown block assembly illustrated in Figs. 23 and 24 is hoisted into position and locked in the manner described as aforesaid To clear the leg sections during hoisting, the crown assembly is preferably held in offset relation to the superstructure legs during that operation and, when elevated to the necessary height above supporting plates I44, swung around into position so that locating pins I84 may be dropped into the tapered sockets I46 provided therefor.

12 After erection of all the derrick parts heretofore described, a platform for the derrick man may be hoisted into position.

The requisite procedure for disassembly or tearing down the structure'is substantially the reverse of that which has been described herein.

From the foregoing it will be seen that, in addition to the legs of the derrick superstructure and the crown assembly, a number of brace rods and girts are employed to stiffen the derrick and render it truss-like in action against laterally applied forces and strong as a column when subjected to axially applied forces. The design of the several principal derrick parts whereby they may be assembled, while disposed horizontally on the ground, in such relationship to each other that the erection of the entire derrick may be effected, save only the final positioning of certain elements such as the crown assembly and platform, without successively elevating individual structural elements and bolting or riveting them into desired position as heretofore practiced, constitutes an important feature of this invention.

After use for the desired length of time at any particular station, the derrick may be dismantled almost as quickly as it has been erected, and placed upon trucks to be conveyed to some other point where it may be needed. The space required for transport is much less than that space which is required for the various parts of any other derrick of known type. The danger of erection is minimized and this is a most important feature of the invention as it is well known that there is great loss of life within and throughout the oil fields yearly due entirely to accidents occurring in the erection and dismantling of derrick structures.

Naturally, in designing the derrick structure for use in various oil fields, where requirements may vary, it may be deemed desirable to make minor changes in the design and arrangement of the component elements of the invention. Many such changes may be made without departure from the spirit and scope of the invention as it is defined in the accompanying schedule of claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letter Patent is:

1. The combination of a tubular socket attached to the upper end of a top derrick leg, a gin pole having a collar adjacent its lower end, said socket receiving and supporting the lower end of the gin pole, and adjustment means carried by said collar and engaging the upper end of said derrick leg to hold the gin pole in different positions of angular adjustment with reference to its supporting socket.

2. In combination with a tubular uppermost derrick leg, a plate closing the upper end of the tube, a socket depending from said plate into the tube the axis of the socket intersecting the axis of said tube, and crown bolt receiving openings in said plate outside the confines of the tube wall.

3. A derrick gin pole assembly comprising a plurality of poles adapted for support respectively by the upper ends of derrick legs, a member secured to the upper end of one pole providing sockets adapted to receive the ends of the other poles, said member comprising a rectangular plate one quadrant of which is secured in substantially horizontal position to the end of said pole, plates secured to and depending fromthe 13 under face of said horizontal plate forming sockets beneath the other quadrants thereof, and means secured to the upper ends of the other poles forming plugs receivable in said sockets.

4. That method of erecting and bracing a derrick having a superstructure of supporting legs composed of extensible telescopic sections, a crown assembly, "and a. gin pole assembly at the top, which comprises'the steps of positioning a gin pole for limited axialrotation on the innermost section of each leg prior to erection, successively extending corresponding sectiOnS of each leg, bracing each superstructure section as erected, rotating 'saidwpoles to group and center theupper ends thereof, securing each of said poles so positioned against rotation with .reference to its supporting leg section by means bearing on such section, supporting the crown'assembly by said gin poles, and hoisting the same into position 'upon the upper ends of the upper leg sections.

5. A derrick structure comprising supporting legs each composed of a plurality of extensible telescopic leg sections, means for independently extending each section of each leg, means for securing the same in extended position, a gin pole socket and a crown-positioning socket secured to the upper end of each innermost leg section the gin pole sockets being positioned exteriorly of the crown positioning sockets, a crown assembly including depending locating pins received within the positioning sockets, and gin poles seated at their lower ends within the sockets provided therefor.

6. A derrick gin pole assembly comprising a plurality of poles rotatably supported in the upper sections, respectively, of the telescopic legs of a derrick, said poles having tapered end portions capable of meeting at an apex, a plural socket member secured to the free end of one pole, means on the free ends of the other poles adapted for reception and positioning in said sockets, and cooperating means on each gin pole and supporting leg for rotatably adjusting the relative position of the two.

7. A derrick gin pole assembly comprising a plurality of poles rotatably supported in the upper sections, respectively, of the telescopic legs of a derrick, and means carried by each pole cooperable with its supporting leg for rotatably adjusting the relative position of the two.

8. In a derrick leg the combination of a plurality of tubular telescoping leg sections of successively reduced diameter, a plug secured within the lower end of an inner section, said plug including an opening therethrough and a marginal shoulder seated against the lower end of the section, an opening in the wall of the tube section above said plug, a pulley secured to and extending outwardly from the upper end of the next adjacent outer leg section, and a hoisting cable anchored below and extending through the plug opening, the free end of said cable extending through the opening in the tube wall, between the telescoped sections and passing over said pulley.

9. The method of erecting a derrick having four legs each comprising a plurality of telescoping sections and the uppermost section of which has a gin pole mounted thereon, one such gin pole having amxed to its upper end a member provided with downwardly opening sockets for the reception of the upper ends of the other three gin poles, which comprises, extending as a preliminary operation, to the upper limit of its asseyovc 14 travel, the upper leg section which carries the socketed member, and thereafter projecting upwardly the upper sections of the remaining legs to cause the upper ends of the gin poles carried thereby to enter the sockets of said socketed member.

10. The method of erecting a derrick having fourlegs each comprising a plurality of telescoping sections and the uppermost section of which has a ginpole mounted thereon, one such gin pole having affixed to its upper end a member provided with downwardly opening sockets for the reception of "the upper ends of the other three gin poles, which comprises, extending as a preliminary operation, "to *the upper limit of its travel, the upper leg section which carries the socketed member, thereafter projecting upwardly "the upper sections of the remaining legs to cause the upper ends of the gin poles carried thereby to enter the sockets of said socketed member, and finally equalizing the pressures of the gin poles last raised against said socketed member.

11. In a derrick, in combination, four legs each comprising a plurality of telescoping sections, a gin pole mounted upon the uppermost section of each leg, and a member fixed upon the upper end of one such gin pole, said member having downwardly opening sockets for the reception of the upper ends of the other gin poles whereby, after said member has been raised to final position by elevation of the leg section to which it is attached, the assembly may be completed by raising the remaining gin poles and causing the upper ends thereof to enter the sockets of said member.

12. The combination set forth in claim 11 in which said member carries adjustable means for engaging the upper ends of the three gin poles assembled therewith whereby any load applied to said member may be equally distributed to the four gin poles.

13. A gin pole construction for derricks comprising, in combination with the main derrick structure, four gin poles, a member affixed to the upper end of one such pole and having downwardly opening sockets, three additional gin poles having their upper ends disposed within three such sockets, and. three adjusting elements carried by said member and engaging the upper ends of said three additional gin poles, respectively, said elements being adjustable vertically relatively to said member, whereby any load imposed upon said member can be equally transferred to said gin poles.

14. The combination set forth in claim 13 in which said means comprises three individually adjustable screws with vertically disposed axes.

15. The combination set forth in claim 13 in which said sockets open downwardly and outwardly the walls of said sockets engaging only the upwardly and inwardly facing surfaces of the respective gin poles.

16. In a derrick, in combination, four supporting legs each having a socket at its upper end, four gin poles, one associated with each leg, the lower end of each gin pole being disposed within the socket of the associated leg, each gin pole having a collar adjacent its lower end adapted to seat upon the supporting socket, lugs on opposite sides of each collar and integral therewith, each lug having a threaded opening formed therein, said threaded openings being angularly disposed with reference to eachother, and adjusting screws threaded in said openings, the

15 inner ends of said screws normally engaging the associated leg, whereby each gin pole may be adjusted angularly in its socket and securely held in adjusted position.

I JOHN HART WILSON.-

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 406,470 Putnam July 9, 1889 851,180 Mathewson Apr. 23, 1907 1,021,922 Ellson Apr. 2, 1912 1,141,919 Auchu June 8, 1915 1,539,109 Brandt May 26, 1925 Drake Apr. 27, 1926 Number Number Name Date Clark May 11, 1926 Whittlesey Jan. 24, 1928 Black July 14, 1931 Knupp Apr. 17, 1934 Schwemlein et a1. Jan. 18, 1938 Dietle Apr. 12, 1938 Sharp Oct. 25, 1938 Wilson Nov. 12, 1940 Little July 29, 1941 Claire Aug. 19, 1941 Woody July 28, 1942 Lavin Sept. 8, 1942 FOREIGN PATENTS Country Date Great Britain 1924 Germany 1933

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